lsblk

lsblk

The lsblk command in Unix and Linux is used to list information about all available or the specified block devices. It provides a tree-like structure of storage devices, including information such as the device name, major and minor device numbers, size, type, and mount points. This command is particularly useful for system administrators when managing and configuring disk partitions and other block devices.

Basic Usage

The basic syntax for lsblk is:

lsblk [options] [device...]

• device: The specific device to query. If omitted, lsblk lists all block devices.

Examples

List All Block Devices

To list all block devices:

lsblk

List Detailed Information

To list detailed information, including file system type and mount points:

lsblk -f

List All Devices Including Empty Devices

To include empty devices in the output:

lsblk -a

List Devices in JSON Format

To list devices in JSON format, which can be useful for scripting:

lsblk -J

List Specific Device

To list information about a specific device, such as /dev/sda:

lsblk /dev/sda

Options

• -a: Include empty devices.

• -b: Print sizes in bytes rather than in a human-readable format.

• -d: Print only the device name without any partition information.

• -e: Exclude devices with specified major numbers.

• -f: Print file system information.

• -h: Print a help message and exit.

• -J: Use JSON output format.

• -l: Use list format output.

• -m: Print minimum I/O size, optimal I/O size, and physical sector size.

• -n: Do not print the header line.

• -o: Specify which columns to print.

• -P: Use pairs format output.

• -r: Print raw output without tree formatting.

• -t: Print the topology information.

• -x: Print exclusive device information.

Practical Use Cases

Checking Disk Layout

To understand the layout of your disk, including partitions and mount points:

lsblk

Verifying Filesystem Information

To verify the file system type and UUID of your devices:

lsblk -f

Scripting and Automation

To use the output in scripts, especially when needing JSON format:

lsblk -J

Excluding Specific Devices

To exclude certain devices, like loop devices, from the output:

lsblk -e 7

Examples with Explanations

Displaying Full Disk Information

To display all block devices with detailed information about file systems:

lsblk -a -f

• -a: Includes empty devices.

• -f: Shows file system information.

Using Specific Columns

To display only specific columns, such as name, size, and mount points:

lsblk -o NAME,SIZE,MOUNTPOINT

• -o: Specifies the columns to print.

JSON Output for Automation

To get the output in JSON format for further processing in scripts:

lsblk -J

• -J: Uses JSON output format.

Summary

The lsblk command is a powerful tool for listing information about block devices in Unix and Linux systems. It provides a clear overview of the storage devices, their partitions, file systems, and mount points. Mastering lsblk helps in effectively managing and troubleshooting storage-related issues, making it an essential command for system administrators.

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